8

I have a Employee table like

emp_id bigint,
reports_to bigint,
emp_name varchar(20),
Constraint [PK_Emp] Primary key (emp_id),
Constraint [FK_Emp] Foreign key (reports_to) references [MSS].[dbo].[Emp]([emp_id])

emp_id         reports_to        emp_name
------         ------       --------------
1              null         Sumanta
2              1            Arpita
3              null         Pradip
4              1            Sujon
5              2            Arpan
6              5            Jayanti

I want to get all the employees that directly or indirectly reports to Sumanta or emp_id(1), and with hierarchy level, like this:

emp_id         hierarchy_level         emp_name
------         ---------------        ----------
2                    1                  Arpita
4                    1                  Sujon
5                    2                  Arpan
6                    3                 Jayanti

I am new to SQL and just couldn't find what to use or how to get those results. Is it worth a stored procedure with table valued variable, or just a Tsql select query will be enough. Any help is most welcome.

All I have done is-

Select Ep.emp_id,ep.emp_eame 
From Emp as E 
Inner Join Emp as Ep on Ep.reports_to=E.Emp_id 
Where E.reports_to=1 or E.emp_id=1;

but this is accurate upto 2 level and I cant even generate the hierarchy_level no. Any suggestion, idea............ will be most helpfull.........

4

2 回答 2

16

您可以使用递归 CTE：

; with  CTE as 
        (
        select  emp_id
        ,       reports_to
        ,       emp_name
        ,       1 as level
        from    Emp
        where   emp_name = 'Sumanta'
        union all
        select  child.emp_id
        ,       child.reports_to
        ,       child.emp_name
        ,       level + 1
        from    Emp child
        join    CTE parent
        on      child.reports_to = parent.emp_id
        )
select  *
from    CTE

SQL Fiddle 的示例。

于 2013-04-26T09:04:08.847 回答
0

使用 Common_Table_Expression 我们可以这样写

WITH Employee_CTE(employeeid,hierarchy_level,name) AS  
(  
   SELECT employeeid,1 as level,name from employee where employeeid=1 
   UNION ALL  
   SELECT e.employeeid,level +1, e.name 
   from employee e   
   INNER JOIN Employee_CTE c ON e.employeeid = c.managerid  
)  
SELECT * FROM Employee_CTE order by employeeid
于 2020-09-20T17:56:13.763 回答